The
cartridge case is the very heart of reloading. It is the one completely
reusable component that makes the practice of reloading
feasible. The concept of metal-cased, or fixed ammunition
is actually a relatively recent development. First produced in viable
forms in the early 1850s, todays modern cartridge has its
roots in the .22 Short Rimfire. The idea of a cartridge,
however, is by no means new. The use of pre-measured charges of
gun powder and bullet rolled into paper cartridges is believed to
date back to the early 1600s, when King Gustavus Aldophus of Sweden
ordered his soldiers to carry their ammunition in this manner. In
fact, the word cartridge, is derived from the Latin
word for paper, charta. The goal of carrying fixed ammunition
was to provide more consistent charges than might otherwise be obtained
by dumping the powder from a horn or flask, to reduce the spillage
associated with using a powder measure in the field, and most importantly
to expedite the soldiers rate of fire. In use, the cartridge
was torn open, and the powder contained in it was dumped down the
barrel. The ball/bullet was then rammed down on top of the powder,
with the cartridge paper sometimes being used as a wadding between
powder and bullet. In the two-hundred plus years that this system
of loading was widely used, various materials were used in lieu
of paper, including linen and silk. Over the years these paper cartridges
progressed to combustible cartridges, which were widely used in
the American Civil War. Made from nitrated paper or linen, the combustible
cartridges were loaded (from either the muzzle or breech, depending
on the guns design) into the firearm whole, and completely
consumed upon firing. Combustible cartridges were made for a wide
variety of weapons at this time, particularly revolvers. The best
known are probably the linen cartridges used in the Sharps rifles
and carbines.

Combustible
cartridges solved many of the problems associated with carrying
loose powder, but they were still fragile, and had to be handled
with care. They were susceptible to moisture, and could be easily
damaged during the loading process. The combustible cartridge was
a major step forward, but was clearly not the final answer. As various
types of case materials were tried, metallic cartridges came into
being. Some of the original metallic cases were formed from extremely
thin materials, such as foil. Although the foil solved many of the
problems associated with moisture, they were still fairly fragile.
As the mechanisms for repeating firearms developed, stronger cases
that were able to withstand cycling and loading through the action
evolved.

There
were a number of fascinating case designs developed during the years
between 1840 and 1865, with varying degrees of success. Systems
developed during this period included the Pinfire, Teat Fire, Morse,
Inside Pinfire and a host of others. Most were fragile, complicated
and not readily adaptable to the advances in firearms design that
were also taking place. There was even some experimentation with
the caseless concept, such as the caseless Volcanic
cartridge. The Volcanic used what amounted to a Minie ball that
had its hollow base filled with powder, and sealed with a self contained
primer.

The
most significant development during this period, however, was the
rimfire cartridge. Utilizing a self-contained priming system, rimfires
became tremendously popular in a wide variety of calibers. Ranging
from the Flobert BB cap (essentially a lead BB seated in a percussion
cap), to large military cartridges like the .44 Henry Flat and the
.56-56 Spencer, rimfire cartridges served a wide variety of roles.
Although the rimfire system was a quantum leap forward, it still
had some drawbacks. The manufacture of rimfire cases, even in the
larger calibers, was relatively inexpensive. However, once fired,
they could not be conveniently reloaded. In order to ensure reliable
ignition, the case rim must be thin enough to allow the priming
compound to be crushed by the hammers blow. This in turn limits
the pressures that can be used with this type of ignition system.
While this posed no problem when black powder was the primary small
arms propellant, this weakness doomed the rimfire system for more
powerful applications when smokeless propellants came on the scene.
The use of rimfires today is essentially limited to the familiar
.22 caliber rimfire family of cartridges, which operate at relatively
low chamber pressures.

As
propellants, bullet design, and firearms have evolved, cartridge
design has evolved right along with them. Today, there are three
(3) general shapes of cartridges, which may be further defined by
head type. The three basic case shapes are: bottle-necked designs
such as the .30-06 and the 7mm Remington Magnum, straight-walled
cases such as the .38 Special and the .45-70 Government, and the
least common, the tapered cases such as the 9mm Luger and the .30
Carbine. Individual cartridges may then be further described by
their case head design, which will fall into one of the following
categories; rimmed, semi-rimmed, rimless, belted, and rebated. Each
design was produced for a specific reason, which may or may not
still be applicable today.

Rimmed

Rimmed
cartridges represent the oldest case head design still in widespread
use. As the name implies, a rimmed case is distinguished by a rim
that extends outward
from the head of the case, to a diameter noticeably larger than
the case body. Today, the rimmed case is most commonly associated
with cartridges designed for use in revolvers. The purpose of the
rim (in any type of firearm) is to provide for positive headspacing.
In many of the earliest cartridge designs, case shoulders were very
long and sloping, making them difficult to reliably headspace on
the shoulder.

Some
examples are the .22 Hornet, the .303 British, and the .32-20 WCF.
It should also be remembered that mass production techniques of
this era were not as precise as they are today, and larger tolerances
were commonly encountered. Therim proved to be a remarkably simple
solution to the problem of creating a positive step upon which a
cartridge could be headspaced, and yet was easily manufactured.
Rimmed cartridges have certain drawbacks, but these were of no concern
at the time the design was introduced. The biggest of these is the
difficulty in obtaining reliable feeding from a box type magazine.
The rims tend to interfere with each other during the feeding cycle.
This occurs when the rim of the cartridge being chambered tries
to strip the round beneath it, since the rims do not easily ride
over one another. In box magazine fed rifles, such as the .303 British
Enfield, this is overcome only by careful arrangement of the cartridges
when the magazine is initially loaded. Failure to do so will result
in jams and misfeeds. This is of no concern in single-shots, revolvers,
tubular magazines, and double-rifles, and the rimmed case continues
to serve quite well in all of these applications.

Semi-Rimmed

As
box magazines became more prevalent for military use, some solution
to the feeding problems of rimmed cartridges had to be found. The
semi-rimmed case design represents one of the first steps taken
to solve this problem. The basis of the semi-rimmed design is a
rim only slightly larger than the case body itself. Most of the
bottle-necked cases that were originally designed as semi-rimmed
had more pronounced shoulders than most of the earlier rimmed cartridges.
Within a few short years, production techniques had become consistent
enough that cartridges could
be reliably headspaced off the shoulder alone, causing little further
need for this cartridge type. The Japanese 6.5x50mm Arisaka is a
typical example of a semi-rimmed service cartridge. It is worth
noting that the next Japanese service cartridge, the 7.7mm Arisaka,
was a true rimless design.

Not
all semi-rimmed cases were of bottle-necked design. The semi-rimmed
case was also used in many of the early straight-wall automatic
pistol cartridges designed by John M. Browning. The most popular
of these still in use today are the .25 ACP and the .38 Super.

Belted

The
belted case might be thought of as an alternative to the semi-rimmed
design, as
it was intended to accomplish the same goals. The design is an English
innovation, credited to the gunmaking firm of Westly Richards. Intended
to combine the positive headspacing of a rimmed case, the belted
case gives smooth, reliable feeding from a box magazine. The defining
characteristic of these cartridges is a small band, or belt, around
the head of the case, just ahead of the extractor groove. In use,
the beltacts
in exactly the same manner as a rim. Originally, this was an absolute
necessity, owing to the steeply sloping shoulders of many of the
first belted cases.

At
the time of the belted cases introduction, England was still
making the transition from black powder to smokeless propellants,
in the form of Cordite. Cordite is a long strand double-based propellant,
with the length of the individual kernels equaling the length of
the combustion chamber. In production, small bundles
of Cordite were inserted into a straight-walled case, which was
then necked down to its final shape, and the bullet seated. As a
result of this manufacturing method, most cartridges designed for
use with Cordite have very long, sloping shoulders. Again, this
proved to be no problem, as a large percentage of these cartridges
were being chambered in single-shots or double rifles, and were
of rimmed (or as the British call them, flanged) design.
At approximately the same time, the bolt-action was rising in popularity,
forcing gunmakers to develop a case that would feed reliably from
a magazine. This was the origin of the belted case design. Since
then, it has been a traditional British practice to offer both rimmed
and belted designs of the same cartridge, for use in either double
rifles or bolt actions, as appropriate.

The
first two belted cartridges to gain notoriety here in the U.S. (although
developed decades earlier in England) were the .300 and .375 H&H
Magnums introduced to American shooters in the early thirties. Since
then, the belted case has served as the basis for a great many Magnum
cartridges. In all honesty, the vast majority of these modern magnums
have shoulders that are perfectly adequate for headspacing, leaving
the belt to serve no truly functional purpose. Some examples of
the belted case design are the old .300 H&H, and the newer .300
Winchester and 7mm Remington Magnums. There have been very few examples
of belted pistol cases, other than wildcats such as the .40 G&A.

Rimless

The
most commonly used head design today is that of the rimless case.
Despite the rimless designation, the case does indeed
have a rim to facilitate extraction. In this design, however, the
rim does not extend beyond the case body. Rather, the rim diameter
is approximately equal to the diameter of the case body itself just
ahead of
the extractor groove. Designed for flawless feeding through the
various weapon types that were emerging in the late 1890s, the rimless
case has become the most popular and widely used head type in the
world. With no protruding rims or belts to complicate feeding, the
rimless case has proven itself eminently well suited to later military
developments, such as clip loading, magazine and belt-fed weapons.
The first successful rimless design adopted by the U.S. was the
.30-03 Springfield (redesigned as the .30-06 some three years later),
although the U.S. military had been looking at rimless designs for
at least a decade prior. Rimless service cartridges have been the
standard ever since, progressing from the .30-06 to the 7.62mm NATO/.308
Winchester to the current 5.56mm NATO/.223 Remington.

Rimless
cartridges may be found in either straight-wall or bottle-necked
configurations. Headspace in the bottle-neck designs is based upon
the datum line, or midpoint of the shoulder. To the handloader,
this means that sizing die adjustment is critical to assure proper
and safe functioning of reloaded rimless cartridges. If the shoulder
is pushed back by a die that is adjusted down too far, excessive
headspace will result. This causes poor ignition, accuracy problems,
short case life, and poses a serious safety hazard. Despite these
potential problems, the rimless design is still one of the best
combinations for reliable headspacing, trouble-free feeding, and
adaptability to a wide variety of action types.

In
straight-wall cases, the rimless design has become the standard
for semi-automatic pistols, from the time-honored .45 ACP, right
up to the most modern designs such as the .40 Smith & Wesson.
The straight-wall (and/or tapered) rimless design has also been
used for some rifle cartridges, such as the .30 Carbine. In either
rifle or pistol, positioning (headspacing) of a straight-wall rimless
case is controlled by the case mouth, stopping on a corresponding
ledge on the inside of the chamber. As such, case length is a determining
factor in controlling headspace. Positive headspacing can also be
influenced by the type and degree of crimp. For example, a .45 ACP
case of proper length may headspace reliably if given a slight taper
crimp, yet demonstrate excessive headspace if a heavy roll crimp
were applied. As a rule, cases which headspace on the case mouth
should only be taper crimped, and only slightly at that. At present,
it appears that the rimless case, in either straight-wall or bottle-necked
configurations, will continue to be the most common design for the
foreseeable future.

Rebated

Currently
undergoing a revival in the WSM and ultra mags, the rebated case
is characterized by a rim that is noticeably smaller in diameter
than the case body. The intent of this design is normally to offer
increased case capacity without altering or enlarging an existing
bolt face. The .41 AE is perhaps the best example of the rationale
behind this particular head design.

Developed
by Evan Whilden, then with Action Arms, the .41 AE utilizes the
same case head dimensions as the popular 9mm Luger. By increasing
the case body dimensions
enough to accept a .410 diameter bullet, Whilden gave a substantial
boost in performance to 9mm handguns. By keeping the same head dimensions,
converting a standard 9mm to accept the more powerful .41 AE was
simply a matter of switching barrels, magazines and recoil springs.
No costly modifications to the slide or extractor were required.
In the .284 Winchester, the larger body diameter allowed .280 Remington
performance from a short action, again without modification to the
existing bolt face. While the rebated design is an excellent concept,
it has met with little commercial success.